In the video at the link they say it is a Monolithic Dome. It has three layers. The outer is made of a PVC air form that you fill up with air and then you shoot the foam against. That’s why it is a ‘soft shell.’
From there you place re-bar hangers into the foam and add your re-bar against the foam. Then you shoot gunnite, a type of concrete, against the foam until you cover the re-bar. It usually is about six inches thick by the time you are finished shooting it.
Here’s the build process.
https://www.youtube.com/watch?v=lwK2DU3Tj0E
https://www.youtube.com/watch?v=WP_aeAf3o3A
https://www.youtube.com/watch?v=BXFzDCb78bo
Examples of Monolithic Domes.
https://www.youtube.com/watch?v=-w7KQFR8x3o
ping - interesting